[Intravenous anesthesia--current aspects].

Abstract

Intravenous anaesthesia as a defined technique has become popular in recent years, since new developed drugs and more sophisticated application systems were introduced into clinical practice. However, only a minority of anaesthesiologists really practise this new technique. The scientific basis of continuous intravenous anaesthesia has not been spread widely in the anaesthetic community yet. The following review therefore focusses on recent findings and developments in the field of pharmacology, pharmacokinetics, pharmacodynamics and modern application systems of intravenous anaesthetic drugs. The new opioid remifentanil is described, new aspects in the interpretation of pharmacokinetic data are presented and the concept of context-sensitive halftimes as a parameter to estimate the decrease in clinical effect of intravenous anaesthetics is introduced. Drug effect in clinical anaesthesia is a result of equilibration of the drug with the effect site (Biophase). By means of defining the effect site equilibration time (t1/2ke0 and the drugs concentration at which this effect is achieved (Cp50) the pharmacodynamic properties of each intravenous anaesthetic can be characterised. Computerised pharmacokinetic data can be used to generate stable drug concentrations (target plasma concentration) when connected to an infusion pump. These target controlled systems are able to reach a predefined level rapidly and to maintain it. Thus pharmacodynamic interactions of intravenous drugs can be evaluated. The newly found properties of propofol, such as antiemetic, anticonvulsive and antioxidant, and its present clinical use are described. Finally, modern continuous intravenous anaesthetica techniques have been feasible only by the development of efficient application systems. The text gives an overview of the properties of modern syringe pumps and future developments of "smart" pumps.